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时间:2019-08-03
《16 刚度 硬度 强度strength hardness stifness》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、l强度结构杆件所用材料在规定的荷载作用下,材料发生破坏时的应力称为强度。根据外力作用方式不同,材料的抗拉强度、抗压强度、抗剪强度等。StrengthDefinition:Inmaterialsscience,thestrengthofamaterialisitsabilitytowithstandanappliedloadwithoutfailureorplasticdeformation.Materialstrengthreferstothepointontheengineering stress–straincurve (yieldstre
2、ss)beyondwhichthematerialexperiencesdeformationsthatwillnotbecompletelyreverseduponremovaloftheloadingandasaresultthememberwillhaveapermanentdeflection.Theultimatestrengthreferstothepointontheengineeringstress–straincurvecorrespondingtothestressthatproducesfracture.l刚度刚度是指材料
3、或结构在受力时抵抗弹性变形的能力。是材料或结构弹性变形难易程度的表征。在宏观弹性范围内,刚度是零件荷载与位移成正比的比例系数,即引起单位位移所需的力。一个结构的刚度(k)是指弹性体抵抗变形拉伸的能力。计算公式:k=P/δP是作用于结构的恒力,δ是由于力而产生的形变。刚度的国际单位是牛顿每米(N/m)StiffnessDefinition:Stiffness istherigidityofanobject—theextenttowhichitresists deformation inresponsetoanapplied forceThesti
4、ffness, k,ofabodyisameasureoftheresistanceofferedbyanelasticbodytodeformation.Foranelasticbodywithasingle degreeoffreedom (DOF)(forexample,stretchingorcompressionofarod),thestiffnessisdefinedaswhere,F istheforceappliedonthebody,δisthe displacement producedbytheforcealongthes
5、amedegreeoffreedom(forinstance,thechangeinlengthofastretchedspring)Inthe InternationalSystemofUnits,stiffnessistypicallymeasuredin newtons permeter.InImperialunits,stiffnessistypicallymeasuredin pounds(lbs)perinch.l弹性模量一般地讲,对弹性体施加一个外界作用,弹性体会发生形状的改变(称为“应变”),“弹性模量”的一般定义是:应力除以应
6、变。杨氏模量(Young'smodulus),又称拉伸模量(tensilemodulus)是弹性模量(elasticmodulusormodulusofelasticity)中最常见的一种。公式记为E=σ/ε其中,E表示杨氏模数,σ表示正向应力,ε表示正向应变。杨氏模量The modulusofelasticityDefinition:The modulusofelasticity (alsoknownasthe elasticmodulus,the tensilemodulus,or Young'smodulus)isanumberthatm
7、easuresanobjectorsubstance'sresistancetobeingdeformedelastically(i.e.,non-permanently)whena force isappliedtoit.Theelasticmodulusofanobjectisdefinedasthe slope ofitsstress–straincurve intheelasticdeformationregion:[1] Astiffermaterialwillhaveahigherelasticmodulus.Anelasticmo
8、dulushastheformWhere, stress istheforcecausingthedeformationdividedbytheare
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